I gave up my SOT in 2002. So, I've not paid much attn to pre samples. Back then there was no shortage of post 18s. I knew numerous SOTs with them. Must have been easier then. Don't know.
I think that some depts get convinced to purchase them as toys. Some of these guns end up with SOTs as post samples.
I honestly don't understand paying big $ for any post being that it has to go when your SOT goes.
I've heard rumors of a few Pre sample G1 18s. When I was an SOT I was not aware of these. Had I been I would have searched absolutely everywhere for one. I'm a huge fan of factory original (not conversion) guns. Thus, some of my pre sample guns (MP5s, USSS Package UZI, etc) are my very favorites in my collection.
There are tons of MP5 post samples but they're a far more popular gun of course.
One thing I was thinking about was the spare parts issue for an 18. I doubt that Glock would service a post sample but don't know that for sure.
I've been to the G18 Operator School and have fired my SOT friend's guns many times. Love them. They are such an incredible testament to the quality of Glocks. The ones at the school have been fired hundreds of thousands of times. Yet, they bang our 33 rd burst after burst no prob. Incredible guns.
One thing that I'd think would keep the price down - though it obviously does not - is that they are difficult guns to shoot well and control for folks who are not well trained in shooting select fire weapons. Glock used to bring one every year to TAC OPS East before that event was stopped (sucks, was awesome). The G18 demo never lasted long as person after person (all sworn LE or MIL) put rounds in the ceiling after just the first few rounds on full auto mode.
One of my buddies in Europe just purchased a new 18 and 18C no prob. W/VAT etc they're not much over a grand in USD. If only.
Funny that you mention belt feds. I was an Adjunct Instructor at HK ITD later HK D in the early 2000s. I took the MP5 Operator and Instructor Schools with some guys from the Johnson Space Center. They had HK21s in their helos. Some depts do have them!
I posted a thread a while back with many detail pics from the G18 school with the unique parts, manual, etc.
Some have seen this video before but, just to show how much fun these are and how reliable here is a video of me at the G18 Operator School doing a full mag dump....
View: https://www.youtube.com/watch?v=wxQLywdG4m4&feature=youtu.be